Water treatment processes commonly use microbes, mainly bacteria, to catalyze the degradation of unwanted material in wastewater. A feature common to many wastewater treatment processes is the provision of oxygen to a population of microbes. Membrane aerated bioreactors (MABRs), wherein a fixed microbial layer is supported on a gas permeable, water impermeable membrane and oxygen or other gases are fed to the microbes directly through the membrane, have been suggested as an advantageous, fixed biomass process for wastewater treatment. Both hollow fiber and flat sheet type membrane elements, similar to those used in water filtration applications, have been suggested for use in MABRs.